闻香识主人：嗅觉记忆能触发动物喜怒哀乐

If your dog looks pleased to see you – it is probably because it loves the particular way you smell.

The odour of a familiar human apparently lingers like perfume in the animal’s brain – where it triggers an instinctive emotional response, research published yesterday reveals.

Our scent acts on a part of the canine brain associated with reward and the strongest reactions are produced by humans that pets know best, say scientists in America.

Gregory Berns, of Emory University in Atlanta, said: ‘While we might expect that dogs should be highly tuned to the smell of other dogs, it seems that the “reward response” is reserved for their humans.

'When humans smell the perfume or cologne of someone they love, they may have an immediate, emotional reaction that's not necessarily cognitive.

'Our experiment may be showing the same process in dogs. But since dogs are so much more olfactory than humans, their responses would likely be even more powerful than the ones we might have.

'It's one thing when you come home and your dog sees you and jumps on you and licks you and knows that good things are about to happen.

'In our experiment, however, the scent donors were not physically present.

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'That means the canine brain responses were being triggered by something distant in space and time. It shows that dogs' brains have these mental representations of us that persist when we're not there.'

The university’s experiment - the first of its type - involved 12 dogs of various breeds who underwent brain scans while five different scents were placed in front of them.

The scent samples came from the subject itself, a dog the subject had never met, a dog that lived in the subject's household, a human the dog had never met, and a human that lived in the subject's household.

The familiar human scent samples were taken from someone else from the house other than the handlers during the experiment, so that none of the scent donors were physically present.

The results showed that all five scents elicited a similar response in parts of the dogs' brains involved in detecting smells. Responses were significantly stronger for the scents of familiar humans, followed by that of familiar dogs.

The findings, which were published in the journal Behavioural Processes, showed that dogs reacted strongest to the scent of a familiar human even when they were not there.

Pets trained as help or therapy dogs showed greater brain activity than the other dogs in the test.

Researchers say the findings could improve the way animals who assist wounded veterans or disabled people are selected.

如果你的狗一见到你就显得很开心的话，有可能是因为它喜欢你散发出的独特气味。

根据近日公布的一份研究显示，熟悉的人所散发的气味会如同香水一般深深地存在于动物的脑海里。这些气味会触发大脑内部本能的情绪反应。

美国科学家声称，犬类的大脑中有一块负责“奖励”的区域，与宠物狗最亲密的人身上的气味能够激起该区最强烈的反应。

埃默里大学的格里高利· 伯恩斯(Gregory Berns)说：“我们原以为这种反应是适用于狗之间的。目前看来这种‘奖励反应’只适用于狗的主人。”

“当人们嗅到爱人身上的香水或古龙水时，会立刻出现情绪上的反应，这种反应并不一定能被察觉到。”

“我们的实验或许可以表明，狗对气味的应激过程是相同的。不过鉴于狗的嗅觉比人类灵敏，因此它们对于气味的反应会比人类强烈得多。”

“当你回到家时，你的狗一见到你就会扑到你怀里，不停地舔你，它知道有好事要降临了。”

“但是在我们的实验中，气味样本的源体（狗主人）并不在场。”

“这意味着，犬类的大脑反应是由过去某处发生过的事所触发的。同时也表明，当我们不在狗身边的时候，我们的精神意识形态会留存在它们的大脑中。”

埃默里大学这项开拓性的实验利用了十二只不同品种的狗作为实验对象，通过对这些狗的大脑进行扫描，来研究它们对五种气味的反应有何不同。

气味样本有五个来源，分别是：被测狗自己、被测狗从未见过的另一只狗、居住在被测狗家中的另一只狗、被测狗从未见过的一个人，以及被测狗的家人。

在实验中，气味样本来自被测狗的家人，但他并不参与到实验中来。因此，所有气味样本的源体都没有出现在实验现场。

实验结果显示，狗脑内负责嗅觉的区域对这五种气味都产生了类似的反应。对于熟人的反应尤其强烈，对于熟悉的狗次之。

这项发现被刊登在《行为学过程》杂志上，文中写道，即使熟悉的人没在狗身边，他们的气味也会激发狗最强烈的反应。

在实验中还发现，相比其他种类的狗而言，辅助犬和治疗犬的大脑对气味的反应更为明显。

研究者声称，这些发现对于如何为受伤老兵和残障人士选择合适的辅助犬大有裨益。